Balancing the requirements of food safety with the need to provide an attractive presentation has generated a need for tamper proof, tamper resistant, and tamper evident plastic packaging. Tamper evident packaging uses a mechanism in the packaging itself that allows the package to initially be closed in order to contain the food product, but prevents the opening of the packaging without generating some sort of evidence that the container has been opened.
However, many initial efforts generated a number of problems, including consumer usage problems, distribution problems, and manufacturing problems.
Consumer problems include making the packaging too difficult to open for the consumer, generating sharp edges on the opened packaging which can create a hazard, generating removable strips that can accidentally find their way into the food product and adding plastic waste, failing to provide a large enough tamper signal or change for the consumer to notice the package has been tampered with, complicate opening instruction, making the container unable to be re-closed, and failing to allow food containers to be filled on-site at the supermarket with a mechanism that is easily usable by supermarket staff.
Distribution-side problems include making a container that is not stackable, making containers that require separate lids from bases, requiring training in how to use and handling the tamper-resistant packages without damaging the perforated tear-strip while keeping the tamper-evident features intact, and requiring training of grocery or distribution staff to recognize when a product has been tampered with so that it can be removed from the supply chain.
Manufacturing problems include requiring the use of unusual plastics or expensive manufacturing processes, whether to use an injection molding process, a thermoforming process, or some other process in order to create the necessary features for the container. Such features considered by engineers in the field can include how best to accomplish a bent feature, a fold feature, stiffness vs. flexibility, spring-effects, recesses, channels, raised features, structural ribs, tear-able or frangible features, resilient living hinges, pull-tab features, locking features, and sealing tolerances, to name a few.
A wide of variety of technologies and inventions in this field have attempted to address or provide solutions to some of the problems. One example, from 1959, is U.S. Pat. No. 2,915,214 issued to Frankel ad which discloses a plastic container with a lid and a base with “a sealing rim” as a circumferential engagement mechanism. Both the lid and the base have outwardly extending peripheral flanges, connected by a hinge with “rupturable perforations,” which, when severed, leave “separated ends” to facilitate opening the container. Another example, from 1978, is German Patent No. 7816353 issued to Menshen which discloses a container with a lid connected to a base by a hinge formed of a projection and a perforated tear strip. Removal of the tear strip allows the container to be opened and provides evidence of possible tampering. This method presented a waste of plastics material that ended up in the wasteland. A further example, from 1996, is U.S. Pat. No. 5,507,406 issued to Urciuoli which discloses a resealable, tamper evident container. It employs a circumferential engagement mechanism, where the base includes a breakpoint “in the form of a perforated line, a groove or the like” connecting the base to the lid. Only by severing the breakpoint can the lid be removed, which provides evidence of possible tampering. This invention had a limitation not be able to reclose and reseal the primary products. Finally, from 2006, is U.S. 7,118,003, which discloses a tamper-resistant/evident container having a tamper evident removable structure that connects the cover to the base portion, a removable tear strip, a secondary engagement mechanism inside the perimeter of the base portion that prevents tampering by sealing the cover to the base. This product is not only added the plastic waste of the tear-strip to the landfield, complicated opening instructions and imposed a hazard to consumers from the shape edges of the perforations after the tear-strip removed. Moreover, the invention adds more complexity for the food processors in handling the delicated containers to prevent breakage/tearing perforations between the lid, tear-strip, and the base.
Therefore, there still remains a need within the field for improved plastic containers having tamper-evident features such as the Pull-Tab Tamper Evident Containers.